The invention relates to a turbine housing for an exhaust gas turbocharger of a drive assembly, the turbine housing having at least one spiral channel, that can be coupled to an exhaust gas line of the drive assembly, and a receiving chamber including a turbine wheel which is arranged downstream of the at least one spiral channel and to which exhaust gas can be supplied. The turbine wheel is rotatably supported in the turbine housing and a guide baffle is arranged fixed to the turbine housing in a transition region between the at least one spiral channel and the receiving chamber. The invention further relates to a method for producing a turbine housing.
Such a turbine housing is known from DE 10 2005 027 080 A1. The turbine housing for an exhaust gas turbocharger of an internal combustion engine shown therein has a spiral channel, which can be coupled to an exhaust gas line, of the internal combustion engine. A turbine wheel is arranged downstream of the spiral channel, which turbine wheel is rotatable in the turbine housing around a rotational axis. A guide baffle is arranged fixed to the turbine housing in a transition region between the spiral channel and the turbine wheel. The turbine housing further has an axial slider that can be displaced in the direction of the rotational axis, by means of which the guide baffle can be covered more or less. By displacing the axial slider, a cross section in the transition region through which the exhaust gas flows can be changed. Depending on the axial position of the axial slider, a different turbine inlet cross section can be adjusted. In order to arrange the guide baffle fixed to the turbine housing, the turbine housing is clamped to a bearing housing, in which a shaft is mounted, which is connected to the turbine wheel in a rotationally fixed manner.
Because of the continuing tightening of emission limits, particularly for nitrogen oxides and soot, the requirements of exhaust gas turbochargers or of charged internal combustion engines also increase. Thus, there are growing demands with regard to the charge pressure availability over average to high load ranges of the internal combustion engine, whereby exhaust gas turbochargers have to be more and more decreased in size. In other words, the required high turbine performances of exhaust gas turbochargers are realized by an increase of the retention capability or by a decrease of the intake capability of the exhaust gas turbocharger in connection with the respective internal combustion engine. In order to hereby counteract a decrease of the efficiency of the turbine, the provision of a flow guide baffle in the transition region between the at least one spiral channel and the turbine wheel has proven to be advantageous.
A further influencing of the performance capability of an exhaust gas turbocharger is possible by means of exhaust gas treatment devices arranged in the exhaust gas line downstream of the turbine, which can comprise a particle filter, a catalyst and/or a SCR system (SCR=selective catalytic reduction). These exhaust gas treatment devices lead to a pressure increase at the outlet side of the turbine housing or of the exhaust gas turbocharger. In order to obtain a sufficient turbine pressure drop for providing a satisfying performance of the exhaust gas turbocharger, the pressure upstream of the turbine also has to be increased. The quotient of the pressure in front of the turbine and of the pressure behind the turbine has to be determined hereby as the turbine pressure drop.
A design of the turbine of a particularly small size can hereby satisfy the performance requirement of the compressor side of the exhaust gas turbocharger, but is accompanied by lower efficiencies of the turbine. A certain improvement, in particular for internal combustion engines with exhaust gas recirculation systems, can be achieved with exhaust gas turbochargers known from the state of the art, whose turbine housings comprise two spiral channels through which exhaust gas can flow independently and which are usually formed in an asymmetric manner. The spiral channels are respectively coupled to different exhaust gas strands of the exhaust gas line of the internal combustion engine. However, the spiral channels have also reached such small spiral sizes that the flow losses are very high as a result of wall friction due to the small dimensions. Additionally, certain problems exist with regard to the exhaust gas recirculation capability in connection with the necessary combustion air of the internal combustion engine in particular in the lower to the medium speed range.
It is the object of the present invention to provide a turbine housing of the type mentioned at the outset, where the guide baffle is arranged at the turbine housing in a particularly tight manner.